GULFPORT, Miss. - An influential Mississippi congressman has raised the possibility that the Pentagon has undercounted combat casualties in Iraq after he learned that five members of the Mississippi National Guard who were injured Sept. 12 by a booby trap in Iraq were denied Purple Heart medals.

The guardsmen were wounded by an artillery shell that detonated as their convoy passed the tree in which it was hidden, but their injuries were classified as "noncombat," according to Rep. Gene Taylor, D-Miss. Taylor, a senior member of the House Armed Services Committee, learned of the classification when he visited the most seriously injured of the guardsmen, Spc. Carl Sampson, 35, at Walter Reed Army Medical Center in Washington.

"How could no one have caught this?" Taylor said.

On Nov. 20, shortly after visiting Sampson, Taylor brought the matter to the attention of Gen. Richard B. Myers, the chairman of the Joint Chiefs of Staff, and the Purple Hearts quickly were awarded.

But Taylor said the incident raised concerns that Iraq combat casualties had been understated. He said Myers told him he'd been made aware of similar oversights.

"I'm probably going to send a memo out to the rest of the members of Congress and ask if anyone has had a similar incident," Taylor said Friday. "I just don't want to see anyone else who's been injured get cheated about their Purple Heart."

Defense Department statistics show that as of Thursday, some 2,150 service members had been wounded in action in Iraq, while 354 were injured in nonhostile incidents. Of 441 service members who have died in Iraq, 304 are listed as killed in hostile action; 137 deaths resulted from nonhostile action.

A Pentagon spokesman said the decision to award the Purple Heart was made at a unit level and that he couldn't explain how the misclassification occurred.

Members of the Mississippi National Guard were mystified. "Sampson should have already been awarded a Purple Heart," said Lt. Col. Tim Powell, a spokesman for the Guard. "An improvised explosive device built and placed with the intent to harm American soldiers is hostile."

Sampson, who sustained shrapnel wounds to his face and arms, is now hospitalized in Tampa.